Currently known in the art are several methods for producing an eluent flow in liquid chromatography. A uniform eluent flow in liquid chromatography is an obligatory precondition for carrying-out a chromatographic analysis.
One of methods of producing an eluent flow in liquid chromatography comprises displacement of the eluent through a chromatographic system under pressure.
As the source of pressure use is made of pumps of different designs (cf. Modern Practice of Liquid Chromatography Edited by J.J. Kirkland. Industrial and Biochemical Department E.I. du Pont de Nemours and Company, Wilmington, Delaware, Wiley Interscience, a Division of John Wiley and Sons, Inc., New York, London, Sydney, Toronto, 1971, Chap. 2)
This prior art method has certain disadvantages among which most important are occurence of pulsations and a high cost of the equipment required for carrying it out. Furthermore, in modern liquid chromatography a wide range of pressures is employed to ensure a required rate of flowing of the eluent through a chromatographic column. Variation of the flow rate of the eluent is associated with a delicate and labour-consuming operation of the pump adjustment for a different pressure thus prolonging the analysis duration and hindering the shift from one flow rate of the eluent to another.
Known in the art is a method for producing a uniform flow of an eluent in liquid chromatography by way of displacing the eluent from a container under pressure of a compressed gas which is supplied to a resilient partition or a piston mounted in said container with the eluent.
This prior art method is realized by means of an apparatus for producing an eluent flow in liquid chromatography, e.g. by means of a pneumatic pump comprising a rigid container with a located therein compressible vessel with an eluent. In this pump, a compressed gas is fed into the rigid container thus compressing the vessel and displacing the eluent out of it. In different arrangements of the pump as the compressible vessel use is made of a plastic flask, stainless-steel or teflon bellows (cf. Modern Practice of Liquid Chromatography, Edited by J.J. Kirkland, Industrial and Biochemical Department, E.I. du Pont de Nemours and Company, Wilmington, Delaware, Wiley Interscience, a Division of John Wiley and Sons, New York, London, Sydney, Toronto, 1971, Chap. 2).
However, the above-described prior art method and corresponding apparatus for producing a flow of an eluent in liquid chromatography feature a series of essential disadvantages.
Due to the evolution of the dissolved gases from the eluent, chromatographic parameters are impaired, for example resolution, and stability of operation of the sensor of zero-line fluctuations is hindered.
To practice said prior art method using the above-described apparatus a high-pressure source is required, i.e. a container with a compressed gas. As a result, the whole chromatographic system becomes cumbersome and inconvenient in transportation and lacks its self-dependency.
Said cylinders with compressed gas operate under pressure not exceeding 150 atm, whereby the upper pressure limit of this pump system becomes restricted.